ask-password: add minimal framework to allow services query SSL/harddisk passphrases from the user

1 files changed, 352 insertions, 0 deletions

diff --git a/src/ask-password.c b/src/ask-password.c
new file mode 100644
index 0000000000..2c9b027d00
--- /dev/null
+++ b/src/ask-password.c
@@ -0,0 +1,352 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/socket.h>
+#include <sys/poll.h>
+#include <sys/types.h>
+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+#include <sys/signalfd.h>
+#include <getopt.h>
+
+#include "log.h"
+#include "macro.h"
+#include "util.h"
+
+static const char *arg_icon = NULL;
+static const char *arg_message = NULL;
+static usec_t arg_timeout = 60 * USEC_PER_SEC;
+
+static int create_socket(char **name) {
+        int fd;
+        union {
+                struct sockaddr sa;
+                struct sockaddr_un un;
+        } sa;
+        int one = 1, r;
+        char *c;
+
+        assert(name);
+
+        if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
+                log_error("socket() failed: %m");
+                return -errno;
+        }
+
+        zero(sa);
+        sa.un.sun_family = AF_UNIX;
+        snprintf(sa.un.sun_path+1, sizeof(sa.un.sun_path)-1, "/org/freedesktop/systemd1/ask-password/%llu", random_ull());
+
+        if (bind(fd, &sa.sa, sizeof(sa_family_t) + 1 + strlen(sa.un.sun_path+1)) < 0) {
+                r = -errno;
+                log_error("bind() failed: %m");
+                goto fail;
+        }
+
+        if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
+                r = -errno;
+                log_error("SO_PASSCRED failed: %m");
+                goto fail;
+        }
+
+        if (!(c = strdup(sa.un.sun_path+1))) {
+                r = -ENOMEM;
+                log_error("Out of memory");
+                goto fail;
+        }
+
+        *name = c;
+        return fd;
+
+fail:
+        close_nointr_nofail(fd);
+
+        return r;
+}
+
+static int help(void) {
+
+        printf("%s [OPTIONS...] MESSAGE\n\n"
+               "Query the user for a passphrase.\n\n"
+               "  -h --help         Show this help\n"
+               "     --icon=NAME    Icon name\n"
+               "     --timeout=USEC Timeout in usec\n",
+               program_invocation_short_name);
+
+        return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        enum {
+                ARG_ICON = 0x100,
+                ARG_TIMEOUT
+        };
+
+        static const struct option options[] = {
+                { "help",      no_argument,       NULL, 'h'         },
+                { "icon",      required_argument, NULL, ARG_ICON    },
+                { "timeout",   required_argument, NULL, ARG_TIMEOUT },
+                { NULL,        0,                 NULL, 0           }
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
+
+                switch (c) {
+
+                case 'h':
+                        help();
+                        return 0;
+
+                case ARG_ICON:
+                        arg_icon = optarg;
+                        break;
+
+                case ARG_TIMEOUT:
+                        if (parse_usec(optarg, &arg_timeout) < 0 || arg_timeout <= 0) {
+                                log_error("Failed to parse --timeout parameter %s", optarg);
+                                return -EINVAL;
+                        }
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        log_error("Unknown option code %c", c);
+                        return -EINVAL;
+                }
+        }
+
+        if (optind != argc-1) {
+                help();
+                return -EINVAL;
+        }
+
+        arg_message = argv[optind];
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        char temp[] = "/dev/.systemd/ask-password/tmp.XXXXXX";
+        char final[sizeof(temp)] = "";
+        int fd = -1, r = EXIT_FAILURE, k;
+        FILE *f = NULL;
+        char *socket_name = NULL;
+        int socket_fd, signal_fd;
+        sigset_t mask;
+        usec_t not_after;
+
+        log_parse_environment();
+        log_open();
+
+        if ((k = parse_argv(argc, argv)) < 0) {
+                r = k < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+                goto finish;
+        }
+
+        if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
+                log_error("Failed to create password file: %m");
+                goto finish;
+        }
+
+        fchmod(fd, 0644);
+
+        if (!(f = fdopen(fd, "w"))) {
+                log_error("Failed to allocate FILE: %m");
+                goto finish;
+        }
+
+        fd = -1;
+
+        assert_se(sigemptyset(&mask) == 0);
+        sigset_add_many(&mask, SIGINT, SIGTERM, -1);
+        assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
+
+        if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
+                log_error("signalfd(): %m");
+                goto finish;
+        }
+
+        if ((socket_fd = create_socket(&socket_name)) < 0)
+                goto finish;
+
+        not_after = now(CLOCK_MONOTONIC) + arg_timeout;
+
+        fprintf(f,
+                "[Ask]\n"
+                "Socket=%s\n"
+                "NotAfter=%llu\n",
+                socket_name,
+                (unsigned long long) not_after);
+
+        if (arg_message)
+                fprintf(f, "Message=%s\n", arg_message);
+
+        if (arg_icon)
+                fprintf(f, "Icon=%s\n", arg_icon);
+
+        fflush(f);
+
+        if (ferror(f)) {
+                log_error("Failed to write query file: %m");
+                goto finish;
+        }
+
+        memcpy(final, temp, sizeof(temp));
+
+        final[sizeof(final)-11] = 'a';
+        final[sizeof(final)-10] = 's';
+        final[sizeof(final)-9] = 'k';
+
+        if (rename(temp, final) < 0) {
+                log_error("Failed to rename query file: %m");
+                goto finish;
+        }
+
+        for (;;) {
+                enum {
+                        FD_SOCKET,
+                        FD_SIGNAL,
+                        _FD_MAX
+                };
+
+                char passphrase[LINE_MAX+1];
+                struct msghdr msghdr;
+                struct iovec iovec;
+                struct ucred *ucred;
+                union {
+                        struct cmsghdr cmsghdr;
+                        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
+                } control;
+                ssize_t n;
+                struct pollfd pollfd[_FD_MAX];
+
+                zero(pollfd);
+                pollfd[FD_SOCKET].fd = socket_fd;
+                pollfd[FD_SOCKET].events = POLLIN;
+                pollfd[FD_SIGNAL].fd = signal_fd;
+                pollfd[FD_SIGNAL].events = POLLIN;
+
+                if ((k = poll(pollfd, 2, arg_timeout/USEC_PER_MSEC)) < 0) {
+
+                        if (errno == EINTR)
+                                continue;
+
+                        log_error("poll() failed: %s", strerror(-r));
+                        goto finish;
+                }
+
+                if (k <= 0) {
+                        log_notice("Timed out");
+                        goto finish;
+                }
+
+                if (pollfd[FD_SIGNAL].revents & POLLIN)
+                        break;
+
+                if (pollfd[FD_SOCKET].revents != POLLIN) {
+                        log_error("Unexpected poll() event.");
+                        goto finish;
+                }
+
+                zero(iovec);
+                iovec.iov_base = passphrase;
+                iovec.iov_len = sizeof(passphrase)-1;
+
+                zero(control);
+                zero(msghdr);
+                msghdr.msg_iov = &iovec;
+                msghdr.msg_iovlen = 1;
+                msghdr.msg_control = &control;
+                msghdr.msg_controllen = sizeof(control);
+
+                if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
+
+                        if (errno == EAGAIN ||
+                            errno == EINTR)
+                                continue;
+
+                        log_error("recvmsg() failed: %m");
+                        goto finish;
+                }
+
+                if (n <= 0) {
+                        log_error("Message too short");
+                        continue;
+                }
+
+                if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
+                    control.cmsghdr.cmsg_level != SOL_SOCKET ||
+                    control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
+                    control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
+                        log_warning("Received message without credentials. Ignoring.");
+                        continue;
+                }
+
+                ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
+                if (ucred->uid != 0) {
+                        log_warning("Got request from unprivileged user. Ignoring.");
+                        continue;
+                }
+
+                if (passphrase[0] == '+') {
+                        passphrase[n] = 0;
+                        fputs(passphrase+1, stdout);
+                } else if (passphrase[0] == '-')
+                        goto finish;
+                else {
+                        log_error("Invalid packet");
+                        continue;
+                }
+
+                break;
+        }
+
+        r = EXIT_SUCCESS;
+
+finish:
+        if (fd >= 0)
+                close_nointr_nofail(fd);
+
+        if (socket_fd >= 0)
+                close_nointr_nofail(socket_fd);
+
+        if (f)
+                fclose(f);
+
+        unlink(temp);
+
+        if (final[0])
+                unlink(final);
+
+        return r;
+}